1. Field of the Invention
This invention pertains to the field of polyurethane plastics. The invention more particularly relates to polymer polyols made from alkanolamines, polyether polyols and polyisocyanates.
2. Description of the Prior Art
The use of a polyol in the preparation of polyurethanes by reaction of the polyol with a polyisocyanate in the presence of a catalyst and perhaps other ingredients is well known. Conventional polyols for flexible polyurethane foams are usually made by the reaction of a polyhydric alcohol with an alkylene oxide, usually ethylene oxide and/or propylene oxide, to a molecular weight of about 2000 to 3000 and above. These polyols are then reacted with polyisocyanate in the presence of water or other blowing agents such as fluorocarbons to obtain polyurethane foams (see, for example, U.S. Pat. No. 2,929,800). The prior art describes modified polyols in which vinyl monomers such as styrene or acrylonitrile or other materials such as the reaction products of toluene diisocyanate and hydrazine hydrate have been included to improve the properties of the polyol and thus, the properties of the resulting foam. However, some of these prior art materials are highly toxic and require in addition, stripping of unreacted vinyl monomers or water of hydration. U.S. Pat. No. 4,107,102 describes the manufacture of polyurethane foam using a polyol containing hydrazine and its adducts.
Ureido-polyols for polyurethanes are known to be made simply by reacting an alkanolamine with an organic isocyanate according to U.S. Pat. No. 3,294,751. No solvent polyol seems to be used.
German Offenlegungsschrift No. 2,110,055 discloses a process for making a polyurethane product whereby a hydroxyl-containing amine is included in the formulation in a one-shot process. That is, the hydroxyl-containing amine is simply included initially with the polyol and the polyisocyanate and a polyurethane product results. The German process does not use a polyurea polymer polyol which is then reacted with a polyisocyanate.
U.S. Pat. No. 3,325,421 discloses the method of making a stable dispersion of a urea in a composition comprising an organic polyisocyanate and a compound having at least two alcoholic hydroxyl groups.
Stable dispersions of polyureas can be prepared from mixtures consisting of hydroxyl-group containing materials, polyamines and polyisocyanates as taught by U.S. Pat. No. 4,089,835. The dispersing media may be a polyether, a polyester, a polyester amide or a polycarbonate, while the polyamine should contain primary or secondary amine groups.
British Pat. No. 2,098,229 discloses that polymer polyols for use in urethane foams may be made by reacting triethanolamine with a polyisocyanate in the presence of a polyol solvent. Polyurea polymer polyols made by the reaction of alkanolamines with polyisocyanates in the presence of polyether polyols and absence of a catalyst, may be stabilized by quenching with a secondary amine as described in U.S. Pat. No. 4,293,470.
Other disclosures concerning the production of polymer polyols by the reaction of alkanolamines with polyisocyanates in a polyol solvent are U.S. Pat. Nos. 4,374,209 and 4,296,213. Particularly, the present invention is an improvement on the latter method in that alkoxylated alkanolamines are used to produce polymer polyols more stable than (no phase separation) those of U.S. Pat. No. 4,296,213.